Structure for holding optical fiber

ABSTRACT

A thin member for sealing and holding optical fibers laid two-dimensionally is composed of a base member layer, an adhesive member layer deposited on the base member layer, and a laminate member layer holding the optical fibers between it and the adhesive member layer. The optical fibers are arranged parallel not to be superposed on one another. They are bent individually by 180 degrees at the right-hand end of the thin member, bent downward toward the lower side of the thin member at the area from the central part to the left-hand side part, and led out of the thin member. Hence the structure is thin and therefore can be accommodated in a small space, enabling a small size. If the portions, led out of the thin member, of the optical fibers are covered with tubes, breakage of the optical fibers can be prevented. The thin member can be flexible.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP00/05232 which has an Internationalfiling date of Aug. 3, 2000, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to a structure for integrally holding aplurality of optical fibers.

BACKGROUND ART

Generally, in various devices and modules for optical communication,there is such a case that a plurality of long optical fibers have to becollectively housed in a device.

In order to hold such a plurality of optical fibers in one bundle,conventionally, a process of taking up each of the optical fibers by areel or routing the optical fibers in a casing is performed.

To hold a plurality of optical fibers in one bundle, there is anothercase that an optical fiber ribbon is used. The optical fiber ribbon isobtained by arranging a plurality of optical fibers in parallel,covering the optical fibers with a resin, and forming the optical fibersin a rectangular ribbon shape in cross section. This optical fiberribbon is characterized in that, due to its rectangular shape in crosssection, it cannot be bent in the lateral direction (direction in whichthe optical fibers are arranged in parallel). Conventionally, therefore,by separating the optical fiber ribbon into single optical fibers androuting the optical fibers, housing of the optical fibers isfacilitated.

The conventional structure for holding optical fibers housed in such amanner has, however, the problems as follows.

In the case of using a reel, to prevent occurrence of a loss caused bythe housing, it is necessary to take up the optical fibers orderlyaround the reel. Consequently, it takes time and effort to take up theoptical fibers.

In the case of routing the optical fibers in a device, a work has to bedone while being paid attention so as not to cause entanglement orbreaking of the optical fibers, so that it takes time and effort forhousing.

In the case of using an optical fiber ribbon, since it cannot be bent inthe lateral direction, it is necessary to separate the optical fiberribbon into single optical fibers and route each of the optical fibers.Like the case of simply routing the optical fibers mentioned above, ittakes time and effort for taking up and housing the optical fibers.

Moreover, in any of the cases, the optical fibers cannot be dealt in aplane, a large housing space is required, and it causes such a problemthat the size cannot be sufficiently reduced.

Therefore, an object of the present invention is to facilitate a work ofhousing a plurality of long optical fibers into a device, reduce ahousing space, and accordingly realize a reduced size by enabling theoptical fibers to be handled integrally.

DISCLOSURE OF INVENTION

According to the present invention, an optical fiber is routed in aplane and sealed with a thin member. With the configuration, opticalfibers can be integrally handled without coming apart or gettingentangled as a whole and easily disposed in a device. Since the opticalfibers are sealed with the thin member, a sheet state is obtained as awhole. Consequently, a small housing space is sufficient and a smallsize can be achieved. Moreover, the optical fibers are protected by thethin member, an influence such as a damage can be lessened.

The invention can be easily realized by sandwiching the optical fiber bythe thin member.

The invention becomes more effective in the case of holding a pluralityof optical fibers.

According to the invention, in the improved structure for holding anoptical fiber mentioned above, lengths of the plurality of opticalfibers are set to required lengths. Consequently, a transfer timedifference can be set between optical fibers.

According to the invention, in the improved structure for holding anoptical fiber mentioned above, lengths of the plurality of opticalfibers are set to the same length. Consequently, the transfer time ofthe optical fibers becomes the same, and it becomes unnecessary toconsider a delay difference among the optical fibers.

According to the invention, in the improved structure for holding anoptical fiber mentioned above, an optical fiber in the thin member isprovided with a redundancy area for adjusting the length of the opticalfiber. Thus, the transfer time difference among the optical fibers canbe easily adjusted.

According to the invention, in the improved structure for holding anoptical fiber mentioned above, an end part of the optical fiber led fromthe thin member is covered with a protection tube and this protectiontube is held by the thin member. Since the portion of the optical fiberled out from the end of the thin member can be reinforced and protectedby the protection tube, breakage of the optical fiber in this portioncan be prevented.

In the structure for holding an optical fiber according to theinvention, the thin member can be made of, for example, a material whosemain component is a resin. Further, the thin member can be made of amaterial whose flexibility can be controlled. With such a configuration,according to the degree of mounting to a device, the mounting can befacilitated by arbitrarily controlling the flexibility of the thinmember.

According to the invention, in the improved structure for holding anoptical fiber mentioned above, a connector is attached to an end of anoptical fiber led from the thin member to the outside. It makes theconnection to another device easy.

According to the invention, in the improved structure for holding anoptical fiber above mentioned, an air layer is provided in a portionwhere the optical fibers cross each other in the thin member.Consequently, when the thin member is bent, the air layer functions as abuffer material so that an excessive bending force can be prevented frombeing applied to the optical fibers which cross each other.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing a structure for holding optical fibersaccording to an embodiment of the present invention.

FIGS. 2A and 2B are cross sections of required part in FIG. 1; FIG. 2Ais a cross section taken along line A—A of FIG. 1, and FIG. 2B is across section taken along line B—B of FIG.1.

FIGS. 3A and 3B are a plan view used to describe a case where opticalfibers are stacked in two layers in the structure for holding opticalfibers.

FIG. 4 is a cross section of the structure for holding optical fibers ofFIGS. 3A and 3B.

FIG. 5 is a plan view showing a state where an end part of an opticalfiber, led from a thin member to the outside is covered with a tube inthe structure for holding optical fibers of the invention.

FIG. 6 is a plan view showing a case where a number of optical fibersare stacked and a connector is connected to an end of an optical fiberin the structure for holding optical fibers.

FIG. 7 is a cross section of the structure for holding optical fibers ofFIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

A best embodiment of the present invention will be described in detailhereinbelow with reference to FIG. 1.

FIG. 1 is a plan view showing a structure for holding optical fibers inthe embodiment of the invention. FIG. 2A is a cross section taken alongline A—A of FIG. 1, and FIG. 2B is a cross section taken along line B—Bof FIG. 1.

In this structure for holding optical fibers, a plurality of (eight inthis example) of long optical fibers 1 are routed in a plane andintegrally sealed and held by a thin member 2. The sealing herein is notlimited to a sealed state where the inside of the thin member 2 is notcommunicated with the outside air but is a concept also including astate where the inside is communicated with the outside air.

Each of the optical fibers 1 is arranged in parallel so as not to beoverlapped with each other at the left end of the thin member 2 having arectangular shape in plan view in the direction parallel to the planedirection of the thin member 2. The optical fibers 1 are introduced intothe thin member 2 in this state. In the right part of the thin member 2,each of the optical fibers 1 is bent backward, thereby changing thedirection of the optical fibers 1 to the opposite direction. At thistime, by making the bending positions of the optical fibers 1 deviatefrom each other in the plane direction of the thin member 2, the bendingpositions are set so as not to be overlapped with each other. Further,the optical fibers 1 are bent downward of the thin member 2 in thepositions from the center to the left end of the thin member 2 and ledout of the thin member 2. By making the leading positions of the opticalfibers 1 deviate from each other in the plane direction of the thinmember 2, the leading positions are set so as not to be overlapped witheach other.

In this structure for holding optical fibers, as shown in FIG. 2B, thereis a part where the end of each optical fiber 1 on the introduction sideand the end of the optical fiber 1 on the leading side cross each otherin the thin member 2. However, at the intersection, the optical fiber 1crosses over the leading portions of all optical fibers in the thinmember 2 as shown in FIG. 2B. Since the optical fibers 2 are not stackedin three or more layers, the structure for holding the optical fibers 1is not so voluminous in the thickness direction.

In the case of the embodiment, the thin member 2 mentioned above isconstructed by including a base material layer 4 made of a resinmaterial such as PET (polyethylene terephthalate), an adhesive materiallayer 6 obtained by applying a silicon adhesive or the like on the basematerial layer 4, and a laminate material layer 8 arranged over theadhesive material layer 6 so as to sandwich the optical fibers 1.

To obtain the structure for holding the optical fibers as shown in FIGS.1, 2A and 2B, a plurality of optical fibers 1 are prepared. In thiscase, the lengths of each optical fibers 1 are set according to varioustransfer time differences. Consequently, transmission time can be set asrequired. In setting of the length, according to a system used, highprecision may be required or an allowance to a certain degree may begiven.

The lengths of each optical fibers 1 may be set to be the same. Sincethe transfer time of each optical fibers 1 becomes the same, it isunnecessary to consider variations in delay in the optical fibers 1 inthe thin member 2. Consequently, it makes a work of connecting theoptical fibers 1 to another device convenient.

As described above, the plurality of optical fibers 1 are routed on theadhesive material layer 6 on the thin member 2 while being deviated fromeach other in a plane so as to reduce the overlapped areas and, afterthat, the adhesive material layer 6 is covered with the laminatematerial layer 8. Consequently, the laminate material layer 8 and theadhesive material layer 6 are bonded in a state where the optical fibers1 are sandwiched by them, and the optical fibers 1 are integrally sealedand held by the thin member 2.

At this time, as shown in FIG. 2B, in the portion where the opticalfibers 1 are overlapped and cross each other, an air layer 10 ispositively interposed between the adhesive material layer 6 and thelaminate material layer 8. The air layer 10 functions as a buffer memberto thereby prevent an excessive bending force from being applied to theoptical fibers 1. Since the excessive bending force on the opticalfibers 1 causes an increase in loss of optical transfer, by providingthe air layer 10, light transmission efficiency can be increased.

By constructing the structure for holding optical fibers as describedabove, the plurality of optical fibers 1 can be integrally handledwithout coming apart or being entangled as a whole and easily disposedin a device. The holding structure has a sheet shape as a whole and,moreover, its thickness is equal to only the total of the outsidediameter of the optical fiber 1 and the thickness of the thin member 2except for the overlapped portions of the optical fibers 1. Therefore,the thin structure for holding the optical fibers is achieved. Even inthe case where the structure for holding optical fibers is disposed inthe casing of a device, a small space for housing is sufficient, so thatthe small size can be realized. Moreover, each optical fibers 1 isprotected by the thin member 2, so that an influence such as a damage onthe optical fibers 1 can be lessened.

In the structure for holding optical fibers shown in FIGS. 1, 2A, and2B, depending on the materials of the base material layer 4 and thelaminate material layer 8, there is such a case that affinity for theadhesive material layer 6 is poor and it is difficult to keep highadhesiveness. In this case, it is sufficient to form a coating layerhaving a high affinity for the adhesive material layer 6 on the surfaceof the base material layer 4 and the surface of the laminate materiallayer 8. The coating layer is therefore interposed between the basematerial layer 4 and the adhesive material layer 6 and between thelaminate material layer 8 and the adhesive material layer 6 so that highadhesiveness can be obtained.

In the embodiment shown in FIGS. 1, 2A, and 2B, the number of opticalfibers 1 routed is limited. In order to further increase the number offibers routed, for example, as shown in FIGS. 3A, 3B, and 4, amulti-layer structure may be employed.

First, as shown in FIG. 3A, the plurality of optical fibers 1 are routedon the adhesive material layer 6 formed on the base material layer 4while being deviated from each other in a plane so as to reduce theareas where the optical fibers 1 are overlapped with each other. On theoptical fibers 1, the adhesive material layer 6 is formed and further,as shown in FIG. 3B, the plurality of optical fibers 1 are routed on theadhesive material layer 6 while being deviated from each other in aplane so as to reduce the areas where the optical fibers 1 areoverlapped with each other. The optical fibers 1 are covered with thelaminate material layer 8, and bonding is performed in a state where theoptical fibers 1 in the upper and lower layers are sandwiched by thelaminate material layer 8 and the adhesive material layers 6 and 6.Consequently, the optical fibers 1 are integrally sealed and held. Sincethe optical fibers 1 of the different layers which are laminated aredisposed in different planes, it is not so necessary to deviate theoptical fibers 1 in a plane from those in another plane so as to reducethe area where they are overlapped with each other. Each of FIGS. 3A and3B shows a state where the optical fibers 1 in each layer are routed onthe adhesive layer 6 and 6.

Further, in order to prevent breakage in the led portion of each opticalfiber 1, the configuration as shown in FIG. 5 may be employed.Specifically, the end of the optical fiber 1 led from the thin member 2to the outside is covered with a thin tube 9 made of vinyl or the like.In such a state, one end of the tube 9 is sandwiched by the thin member1. With such a configuration, the end portion of the optical fiber 1 ledfrom the thin member 2 is reinforced, so that breakage can be preventedand the reliability can be enhanced.

By selecting the material of the laminate material layer 8 as that ofthe thin member 2 for example, the thin member 2 can be produced so asto be hard or flexible in accordance with necessity of mounting into adevice. Further, by making the laminate material layer 8 of afire-resistant material, the reliability of a component device can befurther improved.

In the foregoing embodiment, the invention has been described by using,as an example, the structure of routing the plurality of optical fibers1 in a plane and sealing them with the thin member 2. Obviously, it isalso possible to route a single optical fiber 1 in a plane and seal itwith the thin member 2.

As shown in FIGS. 6 and 7, a configuration in which connectors 11 and 12are attached to ends of the optical fibers 1 led from the thin member 2may also be employed.

Specifically, the holding structure of this example is a multi-layerstructure in which the optical fibers 1 are stacked in four layers inthe thickness direction of the thin member 2. The multi-port-connector11 such as MT (Mechanical Transferrable connector) or MPO Multifiberpush-on connector) is connected to one end of each of the optical fibers1 and the single connector 12 such as MU (Miniaure-Unite couplingoptical connector) is connected to the other end. With theconfiguration, connection to other devices is facilitated. In place ofthe single connector 12, a single ferrule can be connected.

Industrial Applicability

According to the invention, a plurality of optical fibers can be handledintegrally without coming part or entangling as a whole and easilyhoused in a device. Since the whole is formed in a sheet state and thin,a small housing space is sufficient, and a small size can be achieved.Moreover, since each optical fiber is protected by the thin member, aninfluence such as a damage can be lessened.

When the lengths of optical fibers are set to required lengths, atransfer time difference can be freely set among the optical fibers inthe thin member.

When the lengths of the optical fibers are set to the same length, thetransfer time of the optical fibers becomes the same. Consequently, itbecomes unnecessary to consider a delay difference in the optical fibersin the thin member.

When the holding part of the optical fiber is set redundantly to adjustthe length of the optical fiber, redundancy is assured in a routing pathof the optical fiber, so that the length of the optical fiber can beadjusted to a required length. That is, the transfer time difference canbe freely set and adjusted.

By covering the end of an optical fiber led from the thin member to theoutside with a tube, breakage of the optical fiber led from the thinmember can be prevented and reliability can be increased.

When the thin member is made of a material whose flexibility can becontrolled, by controlling the flexibility in accordance with the degreeof mounting to a device, the mounting to the device can be facilitated.

By preliminarily providing each optical fiber with a connector,connection to another device becomes easy.

What is claimed is:
 1. A structure for holding an optical fiber,comprising: a thin member; and a plurality of optical fibers sealed witha said thin member, said plurality of optical fibers being set torequired lengths, each of said plurality of optical fibers including anintroduction portion and a leading portion, said introduction portion ofat least one of said Plurality of optical fibers crossing over saidleading portions of said plurality of optical fibers, said leadingportions of said plurality of optical fibers being in a same plane. 2.The structure for holding an optical fiber according to claim 1, whereinsaid thin member including a first layer and a second layer, saidplurality of optical fibers being sandwiched by said first layer andsaid second layer.
 3. The structure for holding an optical fiberaccording to claim 1, further comprising an air layer said air layerbeing in a portion where said introduction portion of said at least oneof said plurality of optical fibers crossing over said leading portionsof said plurality of optical fibers in said thin member.
 4. Thestructure for holding an optical fiber according to claim 1, wherein aconnector is attached to an end part of an optical fiber led from saidthin member.
 5. The structure for holding an optical fiber according toclaim 1, wherein said plurality of optical fibers are set to a samelength.
 6. The structure for holding an optical fiber according to claim1, wherein an optical fiber in said thin member is provided with aredundancy area for adjusting the length of said optical fiber.
 7. Thestructure for holding an optical fiber according to claim 1, wherein anend part of said optical fiber led from said thin member is covered witha protection tube and the protection tube is held by said thin member.8. The structure for holding an optical fiber according to claim 1,wherein said thin member is made of a material whose main component is aresin.
 9. The structure for holding an optical fiber according to claim1, wherein said thin member is made of a material whose flexibility canbe arbitrarily adjusted.